Golf Ball With Hard Cover Layer

ABSTRACT

A golf ball is provided that has a cover layer with an increased hardness. The golf ball may have an inner core made from a highly neutralized polymer. The golf ball may have a four-piece construction, including an inner core, an outer core, a mantle layer, and the cover layer. The cover layer may be made of a thermoplastic polyurethane. The thermoplastic polyurethane cover layer may be formed of a material having a plaque hardness of at least about 44 Shore D. For example, the cover layer may be formed of a material having a plaque hardness of from about 44 to about 50 Shore D, or about 46 Shore D in particular.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a non-provisional application claiming the benefitof priority to U.S. Provisional Application Ser. No. 61/682,757,entitled “Golf Ball with Hard Cover Layer”, filed Aug. 13, 2012, whichis incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates generally to golf balls with an innercore made from a highly neutralized polymer that have a cover layer withincreased hardness.

The game of golf is an increasingly popular sport at both amateur andprofessional levels. A wide range of technologies related to themanufacture and design of golf balls are known in the art. Suchtechnologies have resulted in golf balls with a variety of playcharacteristics and durability. For example, some golf balls have abetter flight performance than other golf balls, in terms of initialvelocity, spin, and total distance.

In recent years, golf balls with high performance resins, in particular,highly neutralized polymer materials, have been introduced into themarket. Highly neutralized acid polymers are known to be used as thematerial for a golf ball core. For example, U.S. Pat. No. 6,653,382 toStatz et al., entitled “Highly Neutralized Ethylene Copolymers and TheirUse in Golf Balls” and filed Oct. 18, 2000, discloses a golf core havingmelt-processable, highly-neutralized ethylene acid copolymers. U.S. Pat.No. 6,756,436 to Rajagopalan et al., entitled “Golf Balls ComprisingHighly-Neutralized Acid Polymers” and filed Apr. 9, 2002, discloses golfballs having highly neutralized acid polymer cores. The disclosure ofthis patent is hereby incorporated by reference. Other conventionalhighly neutralized acid polymers are generally disclosed in U.S. Pat.No. 7,652,086 to Sullivan et al., entitled “Highly-neutralizedThermoplastic Copolymer Center for Improved Multi-layer Core Golf Ball”and filed Feb. 3, 2006, the disclosure of which is hereby incorporatedby reference.

Known golf balls with a core made of highly neutralized polymermaterials may achieve some desirable performance properties. However,different types of golfers may prefer different play characteristic froma golf ball. Namely, some golfers may prefer that a golf ball be softerand thereby achieve increased spin and controllability, at the loss oftotal distance off the tee. On the other hand, other golfers may prefera harder golf ball that achieves lower spin and therefore increasedtotal distance.

Therefore, there exists a need in the art for a golf ball with an innercore made from a highly neutralized polymer that achieves lower rates ofspin when struck by a golf club.

SUMMARY

Generally, this disclosure relates to golf balls that have an inner coremade from one or more highly neutralized polymers, while also having acover layer made from a material having a plaque hardness of at least 44Shore D. The increased hardness of the cover layer may enable the golfball to achieve lower rates of spin, and therefore attain a longer totaldistance off the tee.

In one aspect, this disclosure provides a golf ball comprising: an innercore, the inner core encompassing a center of the golf ball and beingcomprised of a highly neutralized polymer; an outer core, the outer corebeing positioned radially outward of the inner core and substantiallysurrounding the inner core; a mantle layer, the mantle layer beingpositioned radially outward of the outer core and substantiallysurrounding the outer core; and a cover layer, the cover layer beingpositioned radially outward of the mantle layer and substantiallysurrounding the mantle layer; wherein the cover layer is made from amaterial having a plaque hardness of at least about 44 Shore D.

In another aspect, this disclosure provides a golf ball comprising: aninner core, the inner core encompassing a center of the golf ball andbeing comprised of a highly neutralized polymer; an outer core, theouter core being positioned radially outward of the inner core andsubstantially surrounding the inner core, the outer core being comprisedof a thermoset polybutadiene rubber; a mantle layer, the mantle layerbeing positioned radially outward of the outer core and substantiallysurrounding the outer core, the mantle layer being comprised of anionomer resin; and a cover layer, the cover layer being positionedradially outward of the mantle layer and substantially surrounding themantle layer, the cover layer being comprised of a thermoplasticpolyurethane; wherein the thermoplastic polyurethane of the cover layerhas a plaque hardness of from about 44 to about 50 Shore D.

Other systems, methods, features and advantages of the disclosure willbe, or will become, apparent to one of ordinary skill in the art uponexamination of the following figures and detailed description. It isintended that all such additional systems, methods, features andadvantages be included within this description and this summary, bewithin the scope of the disclosure, and be protected by the followingclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the disclosure. Moreover, in the figures, likereference numerals designate corresponding parts throughout thedifferent views.

FIG. 1 shows a representative golf ball in accordance with thisdisclosure, the golf ball being of a four-piece construction, having aninner core, an outer core, a mantle layer, and a cover layer;

FIG. 2 is a chart showing various values of the launch angle andbackspin for several example golf balls in accordance with thisdisclosure as contrasted with several comparative example golf ballsthat are not within the scope of this disclosure, for a first testconducted with a driver;

FIG. 3 is a chart showing various values of the launch angle andbackspin for several example golf balls in accordance with thisdisclosure as contrasted with several comparative example golf ballsthat are not within the scope of this disclosure, for a second testconducted with a driver;

FIG. 4 is a chart showing various values of the launch angle andbackspin for several example golf balls in accordance with thisdisclosure as contrasted with several comparative example golf ballsthat are not within the scope of this disclosure, for a test conductedwith a seven iron golf club;

DETAILED DESCRIPTION

This disclosure provides golf balls having an inner core formed from ahighly neutralized polymer and a cover layer formed from a thermoplasticpolyurethane, wherein the cover layer has an increased hardness. Thegolf ball may result in lower spin and therefore longer total distanceoff the tee.

As used herein, unless otherwise stated, certain material properties andgolf ball properties are defined as follows.

The term “hardness” as used herein is measured generally in accordancewith ASTM D-2240 and JIS K 6253. The hardness of a material is taken asthe slab hardness, while the hardness of a golf ball component ismeasured on the curved surface of the molded golf ball component. The“cross-sectional” hardness of a golf ball component is the hardnessmeasured in accordance with the above testing procedures, as measured ona cross-section of a golf ball that has been cut in half. When ahardness measurement is made on a dimpled cover layer, hardness ismeasured on a land area of the dimpled cover layer. Hardness units aregenerally given in Shore D, Shore C, and JIS C, as indicated.

The “coefficient of restitution” or “COR” is measured generallyaccording to the following procedure: a test object is fired by an aircannon at an initial velocity of 40 m/sec, and a speed monitoring deviceis located over a distance of 0.6 to 0.9 meters from the cannon. Afterstriking a steel plate positioned about 1.2 meters away from the aircannon, the test object rebounds through the speed-monitoring device.The return velocity divided by the initial velocity is the COR.

The “flexural modulus” is measured generally in accordance with ASTMD-790.

The “Vicat softening temperature” is measured generally in accordancewith ASTM D-1525.

The “compression deformation” herein indicates the deformation amount ofthe ball under a force; specifically, when the force is increased tobecome 130 kg from 10 kg, the deformation amount of the ball under theforce of 130 kg subtracts the deformation amount of the ball under theforce of 10 kg to become the compression deformation value of the ball.All of the tests herein are performed using a compression testingmachine available from Automated Design Corp. in Illinois, USA (ADC).The ADC compression tester can be set to apply a first load and obtain afirst deformation amount, and then, after a selected period, apply asecond, typically higher load and determine a second deformation amount.Thus, the first load herein is 10 kg, the second load herein is 130 kg,and the compression deformation is the difference between the seconddeformation and the first deformation. Herein, this distance is reportedin millimeters. The compression can be reported as a distance, or as anequivalent to other deformation measurement techniques, such as Atticompression. While the ADC compression testing machine identified abovecan be programmed to perform these compression tests, these types ofcompression tests may also be performed on other testing machines.

Other properties and tests may be conducted as disclosed herein, and asmay be known to a person having ordinary skill in the art of golf ballmanufacturing.

Except as otherwise discussed herein below, any golf ball discussedherein may generally be any type of golf ball known in the art. Namely,unless the present disclosure indicates to the contrary, a golf ball maygenerally be of any construction conventionally used for golf balls,such as a conforming or non-conforming construction. Conforming golfballs are golf balls that meet the Rules of Golf as approved by theUnited States Golf Association (USGA). Golf balls discussed herein mayalso be made of any of the various materials known to be used in golfball manufacturing, except as otherwise noted.

Furthermore, it is understood that any feature disclosed herein(including but not limited to elements of the various embodiments shownin the FIGS. and various chemical formulas or mixtures) may be combinedwith any other features disclosed here, as may be desired, in anycombination, sub-combination, or arrangement.

Finally, as used herein, the terms “about” and “substantially” areintended to account for engineering and manufacturing tolerances.

FIG. 1 shows an embodiment of a golf ball in accordance with thisdisclosure. Golf ball 100 is a four-piece golf ball. Namely, golf ball100 includes inner core 102, outer core 104, mantle layer 106, and coverlayer 108.

Golf ball 100 includes radius 200 that extends from center 101 to outersurface 103. Each component may also have the dimensions as shown inFIG. 1, however FIG. 1 is not necessarily shown to scale. Namely, innercore 102 may have radius 202, outer core 104 may have thickness 204,mantle layer 106 may have thickness 206, cover layer 108 may havethickness 208. The compositions of these layers, and the thicknesses andother properties, are discussed below.

Additional embodiments, not shown, of golf ball in accordance with thisdisclosure may have one or more additional layers or pieces beyond thoseshown in FIG. 1. For example, additional core layers and/or additionalcover layers may be present to form five, six, seven, or even higherpiece balls. Generally, unless otherwise stated herein, the variouslayers of golf balls according to the various embodiments may be madefrom any known golf ball material.

First, inner core 102 may be comprised of a highly neutralized polymer.Highly neutralized polymer compositions, sometimes called highlyneutralized acid polymers or highly neutralized acid polymercompositions, are a type of ionomer.

An ionomer is generally understood as any polymer material that includesionized functional groups therein. Ionomeric resins are often ioniccopolymers of an olefin and a salt of an unsaturated carboxylic acid.The olefin may have from about 2 to about 8 carbon atoms, and may be analpha-olefin. The acid may be an unsaturated monocarboxylic acid havingfrom about 3 to about 8 carbon atoms, and may be an alpha,beta-unsaturated carboxylic acid. Commonly, ionomers are copolymers ofethylene and either acrylic acid or methacrylic acid. In somecircumstances, an additional co-monomer (such as an acrylate ester,i.e., iso- or n-butylacrylate, etc.) can also be included to produce aterpolymer. A wide range of ionomers are known to the person of ordinaryskill in the art of golf ball manufacturing.

When a large portion of the acid groups in the ionomer is neutralized bya cation, the ionomer material may be considered to be a highlyneutralized acid polymer. Generally, such a polymer is considered highlyneutralized when at least 70% of the acid groups are neutralized by acation. In various embodiments, the highly neutralized acid polymer maybe neutralized to at least 75%, at least 80%, at least 85%, at least90%, at least 95%, at least 98%, at least 99%, or substantially 100%.

The acid content of an ionomer, including highly neutralized polymers,is defined as the percentage of unsaturated carboxylic acid by weightrelative to the total weight of the polymer. Generally, the acid contentmay range from 1% to 50%. In general, the acid content is considered“normal” when the acid content does not exceed 15%. In particularembodiments where the ionomer has a “high” acid content, the acidcontent is above 15% but still below 50%. In some embodiments, the acidcontent is considered high when between 20% and 50% or between 20% and40%. Generally, higher acid levels may enable higher densities, buthigher acid levels may also result in a loss of melt-processibility andrelated properties such as elongation and toughness. The acid content ofan ionomer may affect the hardness. Namely, high acid levels may reduceany crystallinity otherwise present in the polymer.

In some embodiments, inner core 102 may comprise only one type orformulation of highly neutralized polymer. In other embodiments, blendsof different types or formulations of highly neutralized polymers invarious percentages are used. The innermost core layer may be made usingany technique known in the art, including but not limited to injectionmolding.

In some embodiments, inner core 102 may generally include one or twohighly neutralized polymer compositions with additives, fillers, andmelt flow modifiers. In some embodiments, inner core 102 generallyincludes HPF resins such as HPF2000 and HPF AD1035, produced by E. I.DuPont de Nemours and Company. In some embodiments, inner core 102includes 100% by weight of HPF AD1035. In some embodiments, inner core102 includes 80% by weight of HPF AD1035 and 20% by weight of additives,fillers, and melt flow modifiers. In some embodiments, inner core 102includes 70% by weight of HPF AD1035 and 30% by weight of HPF2000. Insome embodiments, inner core 102 includes 60% by weight of HPF AD1035,20% by weight of HPF2000, and 20% by weight of additives, fillers, andmelt flow modifiers. In some embodiments, the relative percentages ofHPF AD1035, HPF2000, and additives, fillers, and melt flow modifiers maychange, with HPF2000 ranging from 0% to 100% by weight of thecomposition, HPF AD1035 ranging from 0% to 100% by weight of thecomposition, and/or additives, fillers, and melt flow modifiers rangingfrom 0% to about 25% by weight of the composition.

In a particular embodiment, inner core 102 may comprise a blend ofhighly neutralized polymers, at least one ionomer and optionally weightfillers for adjusting the mass and specific gravity of the ball todesired levels. An inner core may comprise from about 40% to about 85%by weight of a first highly neutralized polymer (such as HPF AD1035),from about 0% to about 45% by weight of a second highly neutralizedpolymer (such as HPF 2000), about 2% to about 8% by weight of an ionomer(such as Surlyn), and about 0% to about 15% by weight BaSO₄ additives.

Inner core 102 may generally have any hardness value. In someembodiments, the hardness is the same throughout the entirecross-section of inner core 102, as the inner core 102 may besubstantially homogeneous.

Generally, the hardness of inner core 102 may be adjusted by changingthe relative amounts of a first highly neutralized polymer and a secondhighly neutralized polymer. For example, a first highly neutralizedpolymer may have a first hardness, and a second highly neutralizedpolymer may have a second hardness. Then, the two highly neutralizedpolymers may be mixed together to form a mixture having a hardness thatis between the first hardness and the second hardness, depending on therelative proportions thereof.

More particularly, in embodiments where inner core 102 is comprised of amixture of two or more types of highly neutralized polymers, therelative amounts of each type of highly neutralized polymer may affectthe cross-sectional hardness. Namely, as the percentage of HPF AD1035relative to HPF2000 increases, the hardness generally decreases. Therelationship of cross-sectional hardness to percentage HPF AD1035 isgenerally linear. In some embodiments, if H is the cross-sectionalhardness and P is the percentage of HPF AD1035 in the inner corecomposition, the relationship between H and P, when HPF AD1035 isblended with HPF2000, is given by the following equation, Eq. 1, withinstandard engineering/manufacturing tolerances: H=78-0.12 P. Thisequation is valid when no masterbatch is used.

Suitable additives and fillers for use with a highly neutralized polymercomposition in inner core 102 may include, for example, blowing andfoaming agents, optical brighteners, coloring agents, fluorescentagents, whitening agents, UV absorbers, light stabilizers, defoamingagents, processing aids, mica, talc, nanofillers, antioxidants,stabilizers, softening agents, fragrance components, plasticizers,impact modifiers, acid copolymer wax, surfactants. Suitable fillers mayalso include inorganic fillers, such as zinc oxide, titanium dioxide,tin oxide, calcium oxide, magnesium oxide, barium sulfate, zinc sulfate,calcium carbonate, zinc carbonate, barium carbonate, mica, talc, clay,silica, lead silicate. Suitable fillers may also include high specificgravity metal powder fillers, such as tungsten powder and molybdenumpowder. Suitable melt flow modifiers may include, for example, fattyacids and salts thereof, polyamides, polyesters, polyacrylates,polyurethanes, polyethers, polyureas, polyhydric alcohols, andcombinations thereof.

In some of the embodiments, inner core 102 may have a diameter ofbetween 20 mm and 35 mm, or between about 24 mm and about 30 mm. FIG. 1shows radius 202, which is half of this diameter value. In particularembodiments, a diameter of inner core 102 may be about 24 mm. In otherembodiments, a diameter of inner core 102 may be about 28 mm. In furtherembodiments, a diameter of inner core 102 may be between about 28 mm andabout 30 mm. Such embodiments may achieve advantageous durability whilehaving no detrimental impact on driver distance.

Next, FIG. 1 shows outer core 104. Outer core 104 is located radiallyoutward of inner core 102, and outer core 104 substantially surroundsinner core 102.

Outer core 104 in some embodiments may have a thickness 204 of at least4.8 mm. In embodiments where inner core 102 is made of a highlyneutralized polymer composition having a diameter ranging from 20 mm to28 mm, if the thickness of outer core 104 is less than about 4.8 mm, thegolf ball may not have sufficient durability. Internal durability may bepreferable when the thickness of outer core 104 ranges from 5.0 mm to 8mm.

In some embodiments, the diameter of the core (inner core 102 and outercore 104 together) may range from about 34 mm to about 40 mm. Inembodiments where inner core 102 is made of a highly neutralized polymercomposition having a diameter ranging from greater than 28 mm to lessthan 40 mm, outer core 104 thickness 204 may be selected to maintain anoverall core diameter of 34 mm to 40 mm. In any of the embodimentsdescribed herein, outer core 104 thickness 204 may be selected to have aconforming golf ball, where the total diameter of the confirming golfball is not less than 1.68 inches.

Outer core 104 may be made using any material, but in some embodimentsmay be made of a thermoset polybutadiene rubber. In some embodiments,outer core 104 may be generally formed by crosslinking a polybutadienerubber composition as described in U.S. Pat. No. 8,193,296, entitledGolf Balls Including Crosslinked Thermoplastic Polyurethane, thedisclosure of which is hereby incorporated by reference in its entirety.

Various additives may be added to the base rubber to form a compound.The additives may include a cross-linking agent and a filler. In someembodiments, the cross-linking agent may be zinc diacrylate, magnesiumacrylate, zinc methacrylate, or magnesium methacrylate. In someembodiments, zinc diacrylate may provide advantageous resilienceproperties. The filler may be used to alter the specific gravity of thematerial. The filler may include zinc oxide, barium sulfate, calciumcarbonate, or magnesium carbonate. In some embodiments, zinc oxide maybe selected for its advantageous properties. Metal powder, such astungsten, may alternatively be used as a filler to achieve a desiredspecific gravity. In some embodiments, the specific gravity of the outercore may be from about 1.05 to about 1.45. In some embodiments, thespecific gravity of the outer core may be from about 1.05 to about 1.35.

In some embodiments, a polybutadiene synthesized with a rare earthelement catalyst may be used to form outer core 104. Such apolybutadiene may provide excellent resilience performance of the golfball. Examples of rare earth element catalysts include lanthanum seriesrare earth element compound, organoaluminum compound, and almoxane andhalogen containing compounds. Polybutadiene obtained by using lanthanumrare earth-based catalysts usually employs a combination of a lanthanumrare earth (atomic number of 57 to 71) compound, such as a neodymiumcompound.

In some embodiments, a polybutadiene rubber composition having at leastfrom about 0.5 parts by weight to about 5 parts by weight of ahalogenated organosulfur compound may be used to form the outer core. Insome embodiments, the polybutadiene rubber composition may include atleast from about 1 part by weight to about 4 parts by weight of ahalogenated organosulfur compound. The halogenated organosulfur compoundmay be selected from the group consisting of pentachlorothiophenol;2-chlorothiophenol; 3-chlorothiophenol; 4-chlorothiophenol;2,3-chlorothiophenol; 2,4-chlorothiophenol; 3,4-chlorothiophenol;3,5-chlorothiophenol; 2,3,4-chlorothiophenol; 3,4,5-chlorothiophenol;2,3,4,5-tetrachlorothiophenol; 2,3,5,6-tetrachlorothiophenol;pentafluorothiophenol; 2-fluorothiophenol; 3-fluorothiophenol;4-fluorothiophenol; 2,3-fluorothiophenol; 2,4-fluorothiophenol;3,4-fluorothiophenol; 3,5-fluorothiophenol 2,3,4-fluorothiophenol;3,4,5-fluorothiophenol; 2,3,4,5-tetrafluorothiophenol;2,3,5,6-tetrafluorothiophenol; 4-chlorotetrafluorothiophenol;pentaiodothiophenol; 2-iodothiophenol; 3-iodothiophenol;4-iodothiophenol; 2,3-iodothiophenol; 2,4-iodothiophenol;3,4-iodothiophenol; 3,5-iodothiophenol; 2,3,4-iodothiophenol;3,4,5-iodothiophenol; 2,3,4,5-tetraiodothiophenol;2,3,5,6-tetraiodothiophenol; pentabromothiophenol; 2-bromothiophenol;3-bromothiophenol 4-bromothiophenol; 2,3-bromothiophenol;2,4-bromothiophenol; 3,4-bromothiophenol; 3,5-bromothiophenol;2,3,4-bromothiophenol; 3,4,5-bromothiophenol;2,3,4,5-tetrabromothiophenol; 2,3,5,6-tetrabromothiophenol; and theirzinc salts, the metal salts thereof and mixtures thereof.

Outer core 104 may be made by any suitable process. For example, in someembodiments, outer core 104 may be made by a compression moldingprocess. The process of making outer core 104 may be selected based on avariety of factors. For example, the process of making outer core 104may be selected based on the type of material used to make outer core104 and/or the process used to make the other layers.

In some embodiments, outer core 104 may be made through a compressionmolding process including a vulcanization temperature ranging from 130°C. to 190° C. and a vulcanization time ranging from 5 to 20 minutes. Insome embodiments, the vulcanization step may be divided into two stages:(1) the outer core material may be placed in an outer core-forming moldand subjected to an initial vulcanization so as to produce a pair ofsemi-vulcanized hemispherical cups and (2) a prefabricated inner coremay be placed in one of the hemispherical cups and may be covered by theother hemispherical cup and vulcanization may be completed. In someembodiments, the surface of inner core 102 placed in the hemisphericalcups may be roughened before the placement to increase adhesion betweenthe inner core and the outer core. In some embodiments, inner coresurface may be pre-coated with an adhesive before placing the inner corein the hemispherical cups to enhance the durability of the golf ball andto enable a high rebound.

Generally, the hardness of a rubber compound may be changed by varyingthe amount of cross-linking agent, such as zinc diacrylate (ZDA) or aperoxide. Varying the cross-linking agent to achieve a particulardesired hardness level for the rubber is within the skill of one havingordinary skill in the art of golf ball manufacturing.

Third, FIG. 1 shows mantle layer 106. Mantle layer 106 is locatedradially outward of outer core 104 and generally surrounds and enclosesouter core 104.

In some embodiments, the mantle layer is made from a thermoplasticmaterial including at least one of an ionomer resin, a highlyneutralized polymer composition, a polyamide resin, a polyester resin,and a polyurethane resin. In some embodiments, the mantle layer isSurlyn®. In some embodiments, the Surlyn used in the mantle layer isnormal acid, having an acid content that does not exceed about 15% byweight. In some embodiments, the Surlyn used in the mantle layer is highacid, having an acid content of between 15% and 50% by weight. In someembodiments, the high acid Surlyn of the mantle layer has an acidcontent of about 20% by weight.

Mantle layer 106 may have any desired thickness 206. In someembodiments, mantle layer thickness 206 may be selected so that the golfball is a conforming golf ball. In some embodiments, mantle layerthickness 206 is between 0.5 and 1.3 mm. In some embodiments, mantlelayer thickness 206 is between about 0.95 mm and about 1.2 mm. In someembodiments, mantle layer thickness 206 is between about 0.5 mm and 0.95mm. In some embodiments, mantle layer thickness 206 is about 0.6 mm. Insome embodiments, mantle layer thickness 206 is about 0.95 mm. In someembodiments, mantle layer thickness 206 is about 1.2 mm.

The combination of acid level and thickness for the mantle layer mayimpact performance. In some embodiments, the mantle layer material isnormal acid and has a thickness of about 0.95 mm. In some embodiments,the mantle layer material is high acid and has a thickness of about 0.95mm. In some embodiments, the mantle layer material is high acid and hasa thickness of about 1.2 mm. In some embodiments, the mantle layermaterial is normal acid and has a thickness of about 1.2 mm. In someembodiments, the mantle layer material is normal acid and has athickness of about 0.6 mm. In some embodiments, the mantle layermaterial is high acid and has a thickness of about 0.6 mm.

Generally, the hardness of mantle layer 106 may be adjusted by varyingthe proportions of the stock materials used to form it. That is, in someembodiments, mantle layer 106 may be formed of a mixture of two or morestock Surlyn materials. In such embodiments, the hardness of mantlelayer 106 may be adjusted by changing the relative amounts of a firstSurlyn ionomer and a second Surlyn ionomer, and additional Surlynionomer(s) if applicable. For example, a first Surlyn ionomer may have afirst hardness, and a second Surlyn ionomer may have a second hardness.Then, the two Surlyn ionomers may be mixed together to form a mixturehaving a hardness that is between the first hardness and the secondhardness, depending on the relative proportions thereof. Generally, theamount of additives does not substantially affect the hardness of amixture of two or more Surlyn ionomers. In some embodiments, mantlelayer 106 may be a mixture of one or more of DuPont's Surlyn ionomersS9150, S8150, and S9320.

Finally, FIG. 1 shows cover layer 108. Cover layer 108 is locatedradially outward of mantle layer 106, and substantially surrounds mantlelayer 106.

Cover layer 108 may be made of any material known in the golf ball art,including but not limited to ionomers such as Surlyn®, urethanes,thermoplastic polyurethanes, balata, and combinations of thesematerials. In some embodiments, outer cover layer 108 is made from acrosslinked thermoplastic polyurethane material that is a blend ofPTMEG, BG, TMPME, DCP, and MDI in varying percentages by weight. “PTMEG”is polytetramethylene ether glycol, having a number average molecularweight of 2,000, and is commercially available from Invista, under thetrade name of Terathane® 2000. “BG” is 1,4-butanediol, commerciallyavailable from BASF and other suppliers. “TMPME” is trimethylolpropanemonoallylether, commercially available from Perstorp Specialty ChemicalsAB. “DCP” is dicumyl peroxide, commercially available from LaPorteChemicals Ltd. “MDI” is diphenylmethane diisocyanate, commerciallyavailable from Huntsman, under the trade name of Suprasec® 1100.Specifically, these materials may be prepared by mixing the componentsin a high agitated stir for one minute, starting at a temperature ofabout 70° C., followed by a 10-hour post curing process at a temperatureof about 100° C. The post cured polyurethane elastomers may be groundinto small chips.

Other suitable outer cover layer compositions are disclosed in thefollowing patent documents, each of which is incorporated herein in itsentirety:

US Patent Publication Number US-2012-0004050, currently U.S. patentapplication Ser. No. 12/829,131 to Yasushi Ichikawa et al., filed onJul. 1, 2010 under the title “Golf Ball Incorporating ThermoplasticPolyurethane”;

US Patent Publication Number ______, currently U.S. patent applicationSer. No. 13/341,544 to Thomas J. Kennedy III, filed on Dec. 30, 2011under the title “Ionomer/Polyamide Alloy for Golf Balls”; and

US Patent Publication Number ______, currently U.S. patent applicationSer. No. 13/342,551 to Yasushi Ichikawa et al., filed on Jan. 3, 2012under the title “Over-Indexed Thermoplastic Polyurethane Elastomer,Method of Making, and Articles Comprising The Elastomer”.

Cover layer 108 may be manufactured using any known technique, includingbut not limited to injection molding, RIM, and compression molding.

Cover layer 108 may have specific hardness ranges or values. Thesehardness values may be expressed as either the plaque hardness of thematerial making up cover layer 108, as measured by ASTM D-2240, or asthe cover layer hardness “on the ball”, that is measured in accordancewith ASTM D-220 except that the measurement is taken on the curvedsurface of the finished ball on a fret between adjacent dimples.

In one embodiment, cover layer 108 may be made from a material having aplaque hardness of at least 44 Shore D. In another embodiment, coverlayer 108 may be made from a material having a plaque hardness of fromabout 44 to about 50 Shore D. In another embodiment, cover layer 108 maybe made from a material having a plaque hardness of from about 46 toabout 50 Shore D. In another embodiment, cover layer 108 be made from amaterial having a plaque hardness of from about 46 Shore D.

In yet another embodiment, cover layer 108 may have a hardness on thegolf ball of from about 60 to about 70 D. In particular embodiment,cover layer 108 may have a hardness on the golf ball of about 64.5 ShoreD. In another embodiment, cover layer 108 may have a hardness on thegolf ball in a range of from about 60 to about 70 Shore D, or from about62 to about 68 Shore D, or from about 63 to about 66 Shore D. In yetstill another embodiment, cover layer 108 and mantle layer 106 have aball hardness difference of less than 10 Shore D.

In a particular embodiment, cover layer 108 may be formed of athermoplastic polyurethane while having the above discussed hardnessranges and values. Further aspects of the cover layer are shown withrespect to the examples, below.

Thickness 208 of cover layer 108 may be any desired thickness. In someembodiments, the thickness 208 may be selected to allow golf ball 100 tobe a conforming golf ball. In some embodiments, the thickness 208 may beselected to enhance the feel of golf ball 100. In some embodiments,thickness 208 may be between about 0.5 mm to about 1.5 mm. In someembodiments, thickness 208 may be about 1.10 mm. While in someembodiments, thickness 208 may be greater than thickness 206.

Golf balls according to this disclosure are provided with dimples on theouter cover layer to enhance the aerodynamic performance of the golfball. Any number of dimples having any shape and depth and in anypattern known in the art may be provided on cover layer 108. In someembodiments, between 200 and 500 dimples may be provided. In someembodiments, between 300 and 400 dimples may be provided. In someembodiments, between 320 and 350 dimples may be provided.

In some embodiments, one or more coating layers may be applied to coverlayer 108. The coating layer(s) may be provided for any reason, such asfor altering a hardness of the cover layer 108, altering theaerodynamics of golf ball 100, enhancing the visibility of golf ball100, and for aesthetic purposes. The coating may be any type of coatingknown in the art, including but not limited to paints, inks, clearcoats, urethane coatings, sparkle coatings, and the like. The coatingmay be applied using any method known in the art, including but notlimited to spraying, stamping, pad printing, brush applications,combinations of these techniques, and the like.

Once assembled, golf balls according to the present disclosure willexhibit various characteristics based upon the construction. Some ofthese characteristics include a ball COR, a ball weight, and a ballcompression.

In particular, golf balls according to the present disclosure havingcover layers with increased hardness may achieve desirable lower ratesof backspin.

This disclosure may be particularly understood in view of the followingexamples, which are not intended to limit the scope of this disclosure.

EXAMPLES

Examples E1 through E12 and comparative examples C1 through C19 wereprepared as discussed below and as shown in Table 1. The results oftesting examples E1 through E12 and comparative examples C1-C19 areshown in Table 2 through Table 4.

Generally, all samples were allowed to age at least 8 weeks aftermanufacturing before testing. All samples were incubated atapproximately 23 C with 0% humidity for 24 hours prior to conducting thetest.

Table 1 below shows the construction for several comparative examples:

TABLE 1 Inner Core Inner Core Mantle Cover Example # Material Size OuterCore Layer layer Dimple C6 75% AD1035 28 mm Rubber - normal 51D 40D N12C7 50% AD1035 28 mm Rubber - normal 58D 40D N12 C8 50% AD1035 28 mmRubber - slightly 51D 43D N12 softer C9 50% AD1035 28 mm Rubber - normal51D 43D N12 C10 50% AD1035 28 mm Rubber - slightly 51D 40D N12 softerC18 100% AD1035  28 mm Rubber - normal 65D 40D N12

Generally, each inner core was made from a composition including one ormore highly neutralized polymers. Specifically, the inner cores were amixture of HPF AD1035 and HPF2000, with minor amounts of additionalSurlyn ionomer added, as well as BaSO₄ additives for weight. The varyingvalues of the hardness were achieved by varying the relative amounts ofAD1035 and HPF2000.

Each outer core was made from a composition of neodymium-catalysedbutadiene rubber (“Nd-BR”). BaSO₄ was added to the outer core to addweight in sufficient amount to meet the USGA mass limitations of theball. Varying hardnesses of the outer core were achieved by varying theamounts of ZDA or peroxide.

Each mantle layer was made from DuPont's commercially available Surlyn.The Surlyn used was a mixture of DuPont's S9150, S8150, and S9320. Thevarying values of the hardness of the mantle layers was achieved byvarying the relative proportions of S9150, S8150, and S9320. Eachexample mantle layer was made from DuPont's commercially availableSurlyn. The Surlyn used was a mixture of DuPont's S9150, S8150, andS9320. The varying values of the hardness of the mantle layers wasachieved by varying the relative proportions of S9150, S8150, and S9320.Descriptions of various mantle layer formulations are provided in U.S.patent application No. 12/627,992 filed on Nov. 30, 2009, and publishedas U.S. Patent Application Number US-2011-0130220-A1, the contents ofwhich is hereby incorporated by reference.

Each cover layer was made from a thermoplastic polyurethane. Examples ofsuch are described in U.S. patent application No. 13/342,551 mentionedpreviously.

Table 2 shows the results of a first Driver Test. The driver test wasconducted in the following manner: 12 samples of each finished golf ballwere hit outdoors with a Golf Labs robot. The tee was approximately 2inches forward of the center of robot and the ball impacted the driverface centered left to right and approximately half an inch above thecenter point of the face. The head speed was approximately 89 mph. Thedriver used was a VR Pro 9.5 degree loft with an extra stiff shaft. Thetrackman net system (radar based launch monitor) was used to gather thedata.

TABLE 2 Driver Test 1 Cover Layer Initial Launch Backspin ExampleHardness Velocity (mph) Angle (°) (rpm) E1 46D 172.9 10.3 2719 E2 46D172.7 10.1 2776 E3 46D 171.7 10.1 2831 E4 46D 172.0 10.1 2800 E5 46D172.3 10.0 2762 E6 46D 172.8 10.1 2773 C1 40D 171.1 9.7 3148 C2 40D171.3 9.7 3090 C3 43D 171.4 9.8 3028 C4 43D 172.7 10.1 2837 C5 40D 172.29.8 2952 C6 40D 172.1 9.7 3071 C7 40D 173.3 9.7 3091 C8 43D 172.5 9.83122 C9 43D 173.1 9.7 3090 C10 40D 172.4 9.5 3240

The data of Table 2 is show in the chart of FIG. 2.

Table 3 shows the results of a second driver test. The second drivertest was conducted in the same manner as the first driver test.

TABLE 3 Driver Test 2 Cover Layer Initial Launch Backspin ExampleHardness Velocity (mph) Angle (°) (rpm) E7 46D 144.6 12.4 2576 E8 46D144.1 12.7 2530 E9 46D 144.2 12.7 2479 E10 46D 144.7 12.7 2564 E11 46D144.6 12.5 2496 E12 46D 144.0 12.6 2484 E13 46D 144.7 12.3 2688 E14 46D144.7 12.4 2525 E15 46D 144.8 12.5 2562 C11 40D 144.7 12.2 2703 C12 43D144.7 12.2 2796 C13 40D 144.3 12.4 2715 C14 40D 144.2 12.3 2628 C15 43D144.2 12.3 2640

The data of Table 3 is shown in the chart of FIG. 3.

Table 4 shows the results of a test using a seven iron. The seven irontest was conducted in the same manner as the first driver test, exceptthat a seven iron club was used instead of a driver.

TABLE 4 Seven Iron Test - 6/7 GL 7 Iron Cover Layer Initial LaunchExample Hardness Velocity (mph) Angle Backspin E7 46D Cover 108.1 18.06977 E8 46D Cover 108.5 18.2 6955 E9 46D Cover 108.4 18.4 6797 E10 46DCover 108.6 18.3 6830 E11 46D Cover 108.7 18.2 6762 E12 46D Cover 108..518.7 6636 C16 40D Cover 107.9 17.7 7326 C17 43D Cover 107.9 17.8 7199C18 40D Cover 108.3 18.0 7052 C19 43D Cover 108.3 17.9 7084

The data of Table 3 is shown in the chart of FIG. 4.

As can clearly be seen in FIGS. 2-4, the example golf balls having ahard cover layer generally achieve lower backspin and increased launchangles as compared to similar golf balls having softer cover layers. Theexample golf balls in accordance with this disclosure may therefore bepreferred by golfers desiring lower spin and longer total distances offthe tee.

While various embodiments of the disclosure have been described, thedescription is intended to be exemplary, rather than limiting and itwill be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the disclosure. Accordingly, the disclosure is not to be restrictedexcept in light of the attached claims and their equivalents. Also,various modifications and changes may be made within the scope of theattached claims.

What is claimed is:
 1. A golf ball comprising: an inner core, the innercore encompassing a center of the golf ball and being comprised of ahighly neutralized polymer; an outer core, the outer core beingpositioned radially outward of the inner core and substantiallysurrounding the inner core; a mantle layer, the mantle layer beingpositioned radially outward of the outer core and substantiallysurrounding the outer core; and a cover layer, the cover layer beingpositioned radially outward of the mantle layer and substantiallysurrounding the mantle layer; wherein the cover layer is made from amaterial having a plaque hardness of at least about 44 Shore D.
 2. Thegolf ball according to claim 1, wherein the cover layer is made from amaterial having a plaque hardness of from about 44 to about 50 Shore D.3. The golf ball according to claim 1, wherein the cover layer is madefrom a material having a plaque hardness of from about 46 to about 50Shore D.
 4. The golf ball according to claim 1, wherein the cover layercomprises a thermoplastic polyurethane.
 5. The golf ball according toclaim 4, wherein the cover layer has a hardness on the ball in a rangeof from about 60 to about 70 Shore D.
 6. The golf ball according toclaim 4, wherein the cover layer has a hardness on the ball in a rangeof from about 63 to about 66 Shore D.
 7. The golf ball according toclaim 4, wherein the golf ball has a launch angle of at least 10.0degrees, and a back spin of less than 3,000 rpm.
 8. The golf ballaccording to claim 1, wherein the mantle layer comprises a high acidionomer.
 9. The golf ball according to claim 8, wherein the inner corecomprises a mixture of at least two different types of highlyneutralized polymers.
 10. The golf ball according to claim 8, whereinthe mantle layer has a thickness that is less than a thickness of thecover layer.
 11. A golf ball comprising: an inner core, the inner coreencompassing a center of the golf ball and being comprised of a highlyneutralized polymer; an outer core, the outer core being positionedradially outward of the inner core and substantially surrounding theinner core, the outer core being comprised of a thermoset polybutadienerubber; a mantle layer, the mantle layer being positioned radiallyoutward of the outer core and substantially surrounding the outer core,the mantle layer being comprised of an ionomer; and a cover layer, thecover layer being positioned radially outward of the mantle layer andsubstantially surrounding the mantle layer, the cover layer beingcomprised of a thermoplastic polyurethane; wherein the cover layer ismade from a material having a plaque hardness of from about 44 to about50 Shore D.
 12. The golf ball according to claim 11, wherein the coverlayer is made from a material having a plaque hardness of from about 46to about 50 Shore D.
 13. The golf ball according to claim 11, whereinthe cover layer is made from a material having a plaque hardness ofabout 46 Shore D.
 14. The golf ball according to claim 11, wherein theouter core has a thickness of at least 4.8 mm.
 15. The golf ballaccording to claim 11, wherein the inner core has a diameter of about28.25 mm, the outer core has a thickness of about 5.20 mm, the mantlelayer has a thickness of about 0.95 mm, and the cover layer has athickness of about 1.10 mm.
 16. The golf ball according to claim 11,wherein the inner core comprises a blend of two highly neutralizedpolymers.
 17. The golf ball according to claim 11, wherein thethermoplastic polyurethane of the cover layer is a crosslinkedthermoplastic polyurethane.
 18. The golf ball according to claim 11,wherein the cover layer and the mantle layer have a ball hardnessdifference of less than 10 Shore D.
 19. The golf ball according to claim12, wherein the inner core has a diameter of from about 20 mm to about30 mm.
 20. The golf ball according to claim 16, wherein the mantle layerhas a thickness that is less than a thickness of the cover layer.